It is known that the cellular immune response plays a role in slowing the progression and spread of neoplasms in experimental animals, but not proven in man. The objectives of our research are to investigate and determine the relationship between cellular immune responses, both tumor specific and general, and the biological behavior of bladder carcinoma. Specifically, we propose to continue our studies to determine whether bladder cancer patients have T-lymphocytes cytotoxic for tumor cells in vitro, whether this cytotoxicity is malignancy related, whether there is a genetic restriction to this cytotoxic T-cell reactivity, whether patients with bladder carcinoma have antigen specific and/or genetically restricted suppressor cells, and to determine the relationship of the major histocompatibility complex (HLA) antigens to these phenomena and to the incidence and biological behavior of bladder carcinomas.